1. Field of the Invention
This invention relates to a recording apparatus such as a heat transfer recording apparatus in which for example, the ink of an ink sheet, is transferred to a recording medium to thereby record the images on the recording medium, and to a facsimile apparatus.
The term "a recording apparatus such as a heat transfer recording apparatus" covers, both a facsimile apparatus as well as apparatuses such as of an electronic typewriter, a copying apparatus and a printer apparatus.
2. Related Background Art
Description will hereinafter be made of a heat transfer printer taken as an example of the recording apparatus.
Generally, a heat transfer printer uses an ink sheet comprising base film having heat-melting (or heat-sublimating) ink applied thereto, and the ink sheet is selectively heated by a thermal head correspondingly to an image signal and the ink melted (or sublimated) is transferred to recording paper to thereby accomplish the recording of images. Generally, this ink sheet is a sheet from which the ink is completely transferred to the recording paper by a single image recording (so-called one time sheet) and therefore, it has been necessary that after the termination of the recording of one character or one line, the ink sheet be conveyed by an amount corresponding to the recorded length and then the unused portion of the ink sheet be reliably brought to a position for recording. This has led to the tendency that the quantity of ink sheet used is increased and when compared with an ordinary thermosensitive printer for recording images on thermosensitive paper, the heat transfer printer has high running costs.
In order to solve such a problem, there have been proposed heat transfer printers in which, as seen in Japanese Laid-Open Patent Application No. 57-83471, Japanese Laid-Open Patent Application No. 58-201686 and Japanese Patent Publication No. 62-58917, recording paper and an ink sheet are conveyed with a speed difference therebetween. As described in these publications, an ink sheet capable of carrying out plural (n) image, recordings (a so-called multiprint sheet) is known and such an ink sheet for reducing the running costs in a heat transfer printer. If such an ink sheet is used, when recording is to be effected continuously over a recording length L, recording can be effected with the length of the ink sheet which is conveyed after or during the recording of each image being made smaller than the length L (L/n:n&gt;1) (this is called multiprinting). In this case, the ink of the ink layer of the ink sheet is heated n times and during each heating cycle, a shearing force is created between the melted (or sublimated) ink of the ink layer and the ink which is not melted (or sublimated) to thereby transfer the ink to the recording paper. The ink of this ink layer is easier to melt as the temperature of the ink becomes higher.
On the other hand, the heat generating element of a thermal head for heating the ink layer is electrically energized and heated when the image information of corresponding recording dots is black. As the amount of black image data to be recorded becomes greater, the time for which the heat generating element of the thermal head is electrically energized becomes longer, and heat is accumulated in the thermal head. In extreme cases, even when the thermal head is not electrically energized, part of the ink of the ink layer of the ink sheet may be melted and transferred to the recording paper, thus causing the "ground stain" of the recording paper or so-called "trail-leaving" which is a phenomenon that when shift is made to the printing of the next line, the ink recorded in the preceding line leaves a trail. This strains the recording paper, which causing deterioration of the quality of recorded images.